Hydrogenation of cleavage effluents in phenol production

ABSTRACT

A method for producing phenol is disclosed which includes oxidizing cumene to form cumene hydroperoxide and acid cleavage to form cumene, phenol, acetone, and various byproducts, including alpha methylstyrene, followed by a subsequent hydrogenation of at least a part of the acetone and substantially all of the alpha methylstyrene.

[0001] The present invention relates generally to improvements in theproduction of phenol whereby coproduced acetone is substantiallyimmediately hydrogenated into recyclable isopropanol byproduct, andalpha methylstyrene byproduct is substantially simultaneouslyhydrogenated into cumene for recycle. In addition, the methods of thisinvention reduce the formation of undesirable byproducts which wouldotherwise reduce product yields and more importantly increase thedifficulty of phenol purification thereby realizing further processefficiencies.

BACKGROUND OF THE INVENTION

[0002] Most of the phenol used in the United States and elsewhere ismade by the oxidation of cumene to form cumene hydroperoxide, followedby decomposition or cleavage of the cumene hydroperoxide to producephenol and yielding acetone as a major coproduct. The first step in thereactor yields cumene hydroperoxide, which decomposes with dilutesulfuric acid or sulfur dioxide to the primary products, plusacetophenone and dimethyl phenyl carbinol. Other processes includesulfonation, chlorination of benzene and oxidation of benzene. Thecompound is purified by rectification.

[0003] Major uses of phenol include production of phenolic resins andpara, para-bisphenol A; as a selective solvent for refining lubricatingoils; in the manufacture of cyclohexanone, salicylic acid,phenolphthalein, pentachlorophenol, acetophenetidine, picric acid,germicidal paints, and pharmaceuticals; as well as use as a laboratoryreagent. Special uses include dyes and indicators, and slimicides.

[0004] The conventional phenol process, which dates back to patents toAllied Chemical and Hercules Chemical Co. in the 1950s, is economical aslong as there is adequate demand for the acetone coproduct. Because theend uses and rate of growth for phenol and acetone differ, however, withphenol generally experiencing higher growth rates, there has long been adesire to produce phenol without acetone.

[0005] In addition, the oxidation of cumene to cumene hydroperoxide(CHP) also results in the formation of some level of dimethylphenylcarbinol (DMPC) also known as dimethylbenzyl alcohol (DMBA). DMPCsubsequently dehydrates in the cleavage system to form alphamethylstyrene (AMS) as a significant process byproduct. The AMS then hasa known tendency to react with the phenol in the cleavage system toproduce cumyl phenol or to dimerize into AMS dimers, both of which areheavier, undesired byproducts, and lead to overall yield loss. Moreover,if an acetone-containing stream is recirculated to an upstream stage,e.g., the cleavage system, the acetone has shown a tendency to formimpurities originating from the acetone such as mesityl oxide orhydroxyacetone.

[0006] Another problem with the conventional processes for preparingphenol is that the conventional cleavage of cumene hydroperoxide ishighly exothermic and requires heat removal to control exotherms,particularly because CHP at higher temperatures can undergo a dangerousthermal decomposition. In conventional processes, cooling can beaccomplished by several methods. In one type of cooling scheme theeffluent, containing approximately stoichiometric levels of acetone andphenol, as well as lesser amounts of AMS, is cooled and recirculated atthe high recirculation ratios (between 20-50:1) that are necessary tocontrol the exotherm. This results, however, in high levels of both AMSand acetone being present under highly reactive conditions, leading tohigh levels of residues, as well as impurities formed from acetonereactions such as aldol condensations.

[0007] Several prior art patents have endeavored to address one or moreof the drawbacks, problems, or limitations of conventional phenolprocesses. U.S. Pat. No. 5,245,090 (DeCaria '090), which is incorporatedherein by reference, teaches a two-stage process for producing phenolcomprising the steps of decomposing cumene hydroperoxide in a firststage, and subjecting the product of the first stage to hydrogenation ina second stage to convert AMS in the first stage effluent stream tocumene, which is then recycled. The DeCaria '090 patent notes (col. 3,lines 25-32) that the first stage effluent stream must be allowed“sufficient contact time in the second reactor to effect essentiallycomplete decomposition of the residual CHP to phenol and acetone andover 95% disappearance of the DMBA (same as DMPC) and DiCup and toeffect virtually complete hydrogenation of AMS . . . to cumene.”Subsequently, DeCaria '090 observes (col. 3, lines 32-26) that this“process can be run . . . with or without the recycle of a portion ofthe acetone product. . . . . ” Clearly, therefore, the DeCaria '090patent does not contemplate the hydrogenation of acetone in thehydrogenation stage. This conclusion is reaffirmed by later portions ofthe DeCaria '090 patent (e.g., col. 6, lines 12-14). Indeed, claim 1 ofDeCaria '090 is specifically directed to a method of making phenol andacetone. Thus, DeCaria '090 does not address the problem of how totransform the acetone coproduct of phenol production into a more usefulproduct or recycle stream or how to reduce formation of undesirablebyproducts. Furthermore, a problem with the DeCaria '090 process schemeis the probable poor selectivity of the hydrogenation in the presence ofcarbonyl compounds. The carbonyl bond in the acetone byproduct can behydrogenated to form isopropanol. Judged strictly as a byproduct,however, isopropanol is of lesser value than acetone. In fact anappreciable though declining percentage of the acetone in the world isproduced from isopropanol as a feedstock.

[0008] U.S. Pat. No. 5,015,786 (Araki '786), which is incorporatedherein by reference, teaches a process for preparing phenol by thecumene process including the step of converting acetone coproduced withthe phenol into isopropanol, thereafter alkylating benzene with theisopropanol and, optionally, with propylene, using a zeolite catalyst toproduce cumene, thereby forming phenol without the usual acetonecoproduct. Araki '786, however, fails to address the problem of how tohandle the AMS component and the other byproduct components of theeffluent from the CHP cleavage/decomposition stage.

[0009] Somewhat similar to Araki '786 is U.S. Pat. No. 5,017,729(Fukuhara '729), which is also incorporated herein by reference.Fukuhara '729 teaches a multi-step phenol production process comprising:(a) reacting benzene with propylene to synthesize cumene, (b) oxidizingthe cumene of step (a) into cumene hydroperoxide, (c) acid cleavingcumene hydroperoxide into phenol and acetone, (d) hydrogenating theacetone of step (c) into isopropanol, (e) dehydrating the isopropanol ofstep (d) into propylene, and (f) recycling the propylene of step (e) tostep (a). It is also possible to take a propylene product from step (e).The acetone byproduct produced upon preparation of phenol is convertedinto propylene which Fukuhara '729 teaches is useful by itself for anyother uses or which may be recycled to the phenol-producing process.Fukuhara '729 is also similar to the Araki '786 patent in failing toaddress the problems of handling the AMS and other byproduct componentsof the effluent from the CHP cleavage/decomposition step.

[0010] U.S. Pat. No. 5,160,497 (Juguin '497), which is also incorporatedherein by reference, teaches still another variation on a phenolproduction process addressed specifically to dealing with theless-desired acetone coproduct. Thus, the Juguin '497 patent observes(col. 1, lines 58-61) that: “Nowadays, the main handicap of this[cumene-to-phenol] process lies in the obligatory coproduction of 0.61ton of acetone per ton of phenol, because the demand for phenolincreases much more rapidly than that for acetone.” The improvement ofthe Juguin '497 patent is stated to be (col. 1, line 66-col. 2, line 2)“in partly or totally hydrogenising the acetone produced into isopropylalcohol, and in recycling at least partly the latter to the stage ofalkylation of benzene where, after dehydration into propene, it will beconverted again into cumene.”

[0011] The Juguin '497 patent further notes, however, that successfulpractice of this invention is highly catalyst dependent because (col. 2,lines 8-12) the conventional alkylation catalysts “are not adapted tothe reaction of alkylation of benzene in the presence of isopropylalcohol because they are very sensitive to water. . . . ” Instead ofusing conventional aluminum chloride or phosphoric acid catalysts,Juguin '497 turns to a specific class of zeolite catalyst which had beenfound to be stable in the presence of the steam generated by dehydrationof isopropyl alcohol.

[0012] The overall method taught by the Juguin '497 patent is amulti-step process comprising in sequence: an alkylation stage (carriedout with at least one catalyst based on a dealuminized Y zeolite havinga particular SiO₂/Al₂O₃ molar ratio) to form an effluent streamcontaining cumene, unreacted benzene, and polyisopropylbenzene; afractionation step to separate a cumene fraction and apolyisopropylbenzene fraction; a transalkylation stage (again carriedout using the particular dealuminized Y zeolite catalyst) wherepolyisopropylbenzene and benzene are reacted to form additional cumene;a further fractionation step to recover the additional cumene fromtransalkylation; an oxidation step to oxidize cumene into cumenehydroperoxide; a cleavage step to cleave the cumene hydroperoxide intophenol and acetone; another fractionation step to separate phenol andacetone; and, finally, the step of hydrogenating the acetone intoisopropyl alcohol in the presence of a nickel-on-silica catalyst, andrecycling the isopropyl alcohol as a feed to the alkylation stage. TheJuguin '497 patent does not address how to handle AMS and otherbyproducts in the effluent from the CHP cleavage stage or how tominimize formation of residue products.

[0013] As a result, there remains an unmet need in this art for anintegrated cumene-based phenol production method that reduces theformation of undesirable byproducts from AMS and acetone. Theaforementioned drawbacks and limitation of the prior art are overcome,in whole or in part, with the methods of this invention for anintegrated, efficient, low-residue phenol process which includeshydrogenation of cleavage effluents.

OBJECTS OF THE INVENTION

[0014] Accordingly, a principal object of this invention is to provideimproved methods, which include a hydrogenation step, for the productionof phenol from cumene.

[0015] It is a general object of this invention to provide an integratedcumene-to-phenol method in which the principal undesirable coproductsand/or byproducts from the cleavage system are converted byhydrogenation into products which can be recycled as feeds to one ormore upstream process steps before they can further react to form otherheavier residues.

[0016] A specific object of this invention is to substantiallysimultaneously hydrogenate, utilizing a suitable hydrogenation catalyst:(a) substantially all of the acetone coproduct in the effluent from thecleavage system of a phenol process to isopropyl alcohol; and (b)substantially all of the alpha methylstyrene byproduct in the cleavagesystem effluent to cumene.

[0017] Other objects and advantages of the present invention will inpart be obvious and will in part appear hereinafter. The inventionaccordingly comprises, but is not limited to, the methods and relatedapparatus, involving the several steps and the various components, andthe relation and order of one or more such steps and components withrespect to teach of the others, as exemplified by the followingdescription and the accompanying drawing. Various modifications of andvariations on the method and apparatus as herein described will beapparent to those skilled in the art, and all such modifications andvariations are considered within the scope of the invention.

SUMMARY OF THE INVENTION

[0018] In this invention, acetone and alpha methylstyrene in theeffluent from the cleavage system of a cumene-based phenol process areboth hydrogenated substantially simultaneously immediately downstream ofthe cleavage system. It is thereby possible to recover isopropanol bydistillation downstream of the hydrogenation step and recycle it back toa benzene alkylation step in place of propylene to produce cumene. Thehydrogenation system of this invention can be integrated with thecleavage system in such a way as to improve overall yield and productpurity. Early hydrogenation of alpha methylstyrene, directly downstreamof the cleavage system, eliminates the active styrenic functionalityfrom forming heavies such as dimers and cumylphenols. Of comparableimportance, elimination of the acetone can reduce the ability of thecomponents in the effluent from the cleavage system to form closeboiling impurities that are difficult to separate from phenol, such ashydroxyacetone, mesityl oxide and methylbenzofuran. Selection ofappropriate hydrogenation catalyst facilitates carrying out theimmediate, substantially simultaneous hydrogenation of acetone and AMSin the effluent from the cleavage system.

BRIEF DESCRIPTION OF THE DRAWING

[0019]FIG. 1 is a process flow diagram schematically illustrating anembodiment of a phenol production process incorporating hydrogenation ofcleavage effluents and recycle of converted products according to thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] The methods of this invention can best be understood by referencefor FIG. 1. As seen in FIG. 1, a stream (such as stream 62) as producedby conventional cumene oxidation technologies, and containing primarilycumene and cumene hydroperoxide, together with lesser amounts ofdimethylphenyl carbinol, acetophenone, and other minor components, isfed to the cleavage reactor system 10. In the cleavage reactor system10, cumene hydroperoxide undergoes an acid-catalyzed decompositionreaction to phenol and acetone. The acid catalyst in reactor 10 mayinclude homogenous acids such as sulfuric acid, sulfur dioxide,hydrochloric acid, nitric acid, or phosphoric acid, or may includeheterogeneous acidic catalysts such as zeolite beta, acidiczeolite-based catalysts, such as MCM-22, MCM-36, MCM-49, MCM-56, ERB-1,ITQ-1, ITQ-2, ITQ-3, SSZ-25, PSH3 and the like, ultrastable zeolite Y,ZSM-5, mordenite, metal oxides, alumina or clays. Usually a smallquantity of water is also present in this stream to achieve the desiredreaction chemistry. In addition to the decomposition reaction of cumenehydroperoxide, the acidic conditions of the cleavage reactor system 10promote the dehydration of the dimethylphenyl carbinol byproduct to formalpha methylstyrene.

[0021] The cleavage system 10 is a highly exothermic reaction whichgenerates heat that may be removed from the effluent stream 12 comingfrom reactor 10 by any number of means known to those skilled in theart. These can include but at not limited to tubular reactors,pump-around cooling, vaporization of the more volatile components,condensation and reflux of the vaporized components, or recycle ofliquid light end components from the downstream process, for example byrecycle stream 36 from separation step 30.

[0022] The acid cleavage reactor effluent 12 contains cumene, phenol,acetone, alpha methylstyrene, water, acetophenone, and other minorimpurities. Stream 12 enters the hydrogenation reactor system 20, wherethe alpha methylstyrene is hydrogenated either partially orsubstantially completely to cumene, and, substantially simultaneously,the acetone is converted either partially or substantially completely toisopropanol. Fresh hydrogen stream 14 together with recycle hydrogenstream 34 from separation system 30 are fed to hydrogenation reactorsystem 20 to provide an excess of hydrogen in the hydrogenation stage.The excess unreacted hydrogen is disengaged at separation stage 30 and,preferably, recycled to hydrogenation stage 20 via recycle stream 34.

[0023] A portion of the isopropanol and/or acetone from stage 30, aswell as possibly acetone 46 from stage 40, may be recycled as stream 36to the cleavage reactor system 10 to facilitate heat removal. Theproduct stream 32 from stage 30, comprising isopropanol and/or acetone,phenol, and cumene (both excess-cumene as well as cumene formed byhydrogenation of AMS), is sent to downstream distillation system 40. Indistillation system 40, stream 32 is separated into the respectiveproducts phenol 44, acetone 46 (if applicable), isopropanol 42 andcumene 45 which is sent to oxidation stage 60. Depending on the acidcatalyst employed, a neutralization step employing an alkaline material,either by direct injection of alkali or by anionic exchange, may also berequired at this point in the process.

[0024] Isopropanol 42 is fed to a cumene process alkylation unit 50 foruse as a benzene alkylating material. Fresh propylene 55 may be neededto supplement the isopropanol 42 as the C3 alkylating agent. Byproductwater 54 and cumene product 52 are produced. The cumene stream 52 fromalkylation system 50 is mixed with cumene stream 45 from stage 40, andthe combined stream 57 is sent to oxidation stage 60, where the cumeneis reacted with oxygen in air feed stream 64 to form cumenehydroperoxide stream 62 for feeding to cleavage reactor 10. Stream 62will typically include about 5-20% of unoxidized cumene plus variousimpurities and byproducts as discussed above.

[0025] The cleavage stage (reference numeral 10 in FIG. 1) according tothe present invention may operate at temperatures of about 50° C. to100° C. Cleavage catalysts suitable for the present invention includesulfuric acid; sulfur dioxide; hydrochloric acid; phosphoric acid,zeolite-type catalyst (e.g., beta; zeolite Y; ZSM-5); acidiczeolite-based catalysts (e.g., MCM-22, MCM-36, MCM-49 and MCM-56);mordenite; acidic clays; and alumina. Feed (stream 62) to cleavage stage10 will typically comprise about 20-95% CHP, 5-20% cumene, and 2-10%DMPC.

[0026] The hydrogenation stage (reference numeral 20 in FIG. 1)according to the present invention may operate at temperatures of about40° C. to 150° C. and at pressures about 50 to 500 psig. Ratios ofhydrogen in stage 20 to the acetone and AMS in effluent stream 12 mayrange from above about 1 to about 30 molar, preferably 3 to 10 molar,thereby representing a molar excess of hydrogen. Suitable catalysts forthe hydrogenation stage 20 of this invention include Group VIIIelements, noble metals, nickel, copper, chromium and combinations andoxides thereof. Hydrogenation stage 20 may be noble metals operated soas to substantially fully or partially convert acetone in stream 12 toisopropyl alcohol.

[0027] The alkylation stage (reference numeral 50 in FIG. 1) may beoperated with feeds of benzene and isopropanol or isopropanol/propylenemixtures at temperatures of about 80° C. to 200° C. in the liquid phaseusing zeolite-type catalysts (e.g., beta and Y) or acidic zeolite-basedalkylation catalysts (e.g., MCM-22, MCM-36, MCM-49, and MCM-56, ITQ-1,ITQ-2, ITQ-3, SSZ-25 and PSH3).

[0028] The acidic zeolite-based alkylation catalysts have been found tohave particular utility in the practice of this invention. The followingU.S. patents and publications, each of which is incorporated herein byreference, teach the preparation and/or use of various acidiczeolite-based catalysts: U.S. Pat. No. 6,096,288 (Roth); U.S. Pat.No.6,077,498 (Diaz Cabañas); WO097/19021 (Corma); U.S. Pat. No.6,063,262 (Dhingra); U.S. Pat. No. 6,049,018 (Calabro); U.S. Pat. No.5,437,855 (Valyocsik); U.S. Pat. No. 5,670,131 (Valyocsik); U.S. Pat.No. 5,362,697 (Fung); U.S. Pat. No. 5,346,685 (Moini); U.S. Pat. No.5,236,575 (Bennett); U.S. Pat. No. 5,068,096 (Valyocsik); U.S. Pat. No.5,104,495 (Chang); U.S. Pat. No. 4,981,663 (Rubin); U.S. Pat. No.4,696,807 (Chu); U.S. Pat. No. 4,791,088 (Chu); U.S. Pat. No. 5,441,721(Valyocsik); U.S. Pat. No. 4,954,325 (Rubin); U.S. Pat. No. 5,173,281(Chang); U.S. Pat. No. 5,043,512 (Chu); U.S. Pat. No. 5,488,194 (Beck);and U.S. Pat. No. 4,439,409 (Puppe); U.S. Pat. No. 4,826,667 (Zones).Several of these patents teach the utility of acidic zeolite-basedcatalysts materials in alkylation and other hydrocarbon processes,although not specifically in connection with cumene-based phenolproduction.

[0029] The oxidation stage (reference numeral 60 in FIG. 1) may beoperated with air and cumene feeds at temperatures of about 60° C. to120° C. and pressures of about 0-100 psig, with cumene recycle to obtainreactor effluent (stream 62) CHP compositions from about 15-35 wt. %CHP. It is preferred to maintain a flowrate of air in air stream 64 tooxidation stage 60 so as to provide about 30% molar excess oxygen instage 60 based on the flow of cumene in feed 57. Excess air is vented byvent stream 65.

[0030] The following example will further illustrate the methods of thepresent invention.

EXAMPLES

[0031] Examples 1A through 3C show the results of hydrogenationexperiments obtained using a batch autoclave. In each example, 5 gramsof catalyst and 150-180 grams of liquid hydrocarbon was charged to a 300ml autoclave. The batch autoclave was equipped with a twin-impelleragitator operating at a speed of 600 RPM. Reactor pressure wasmaintained with a hydrogen cylinder of constant supply pressure. Sampleswere taken at various times throughout the experiment and analyzed viagas chromatography. The feed to the batch hydrogenation reactor in eachexample was chosen to be representative of that to a CHP cleavagereactor when operating with a portion of the feed derived by recyclingsome of the hydrogenation reactor effluent.

Example 1A

[0032] Operating condition: 5 g of Engelhard E-540, a Cu/Mn catalyst,and 150 g of reaction mixture at reaction temperature of 120C andhydrogen partial pressure of 210 psig.

[0033] Feed composition: 36.1 wt % of acetone, 1.1 wt % of isopropanol,19.6 wt % of cumene 4.0 wt % of Alpha-methylstyrene, 0.3 wt % ofdimethylphenylcarbinol (DMPC), and 38.8 wt % of phenol. Reaction Time(hrs) Conversion 1 2 3 5 7.0 Acetone to 2.9 6.8 10.7 17.9 24.9Isopropanol (IPA), % Alpha-methylstyrene 4.0 6.7 10.5 19.0 25.4 (AMS) toCumene, %

Example 1B

[0034] Operating condition: 5 g of Engelhard E-540, a Cu/Mn catalyst,and 150 g of reaction mixture at reaction temperature of 154° C. andhydrogen partial pressure of 170 psig.

[0035] Feed composition: 15.7 wt % of acetone, 22.6 wt % of isopropanol,21.7 wt % of cumene, 1.7 wt % of Alpha-methylstyrene, 0.3 wt % ofdimethylphenylcarbinol (DMPC), and 37.9 wt % of phenol. Reaction Time(hrs) Conversion 1 2 2.5 Acetone to 11.3 23.5 29.9 Isopropanol (IPA), %Alpha-methylstyrene 11.3 23.2 30.0 (AMS) to Cumene, %

Example 2A

[0036] Operating condition: 5 g of copper chromite, ˜42% CuO/˜39% Cr₂O₃purchased from Alfa Aesar, and 180 g of reaction mixture at reactiontemperature of 120° C. and hydrogen partial pressure of 200 psig

[0037] Feed composition: 39.3 wt % of acetone, 0.4 wt % of isopropanol,18.8 wt % of cumene, 3.8 wt % of Alpha-methylstyrene, 0.3 wt % ofdimethylphenylcarbinol (DMPC), and 37.4 wt % of phenol. Reaction Time(hrs) Conversion 1 2.5 4.5 Acetone to 1 2.4 5.4 Isopropanol (IPA), %Alpha-methylstyrene 0 <1 3.6 (AMS) to Cumene, %

Example 2B

[0038] Operating condition: 5 g of copper chromite, ˜42% CuO/˜39% Cr₂O₃purchased from Alfa Aesar, and 180 g of reaction mixture at reactiontemperature of 150° C. and hydrogen partial pressure of 180 psig

[0039] Feed composition: 30.0 wt % of acetone, 4.6 wt % of isopropanol,19.9 wt % of cumene, 3.5 wt % of Alpha-methylstyrene, 0.3 wt % ofdimethylphenylcarbinol (DMPC), and 41.4 wt % of phenol. Reaction Time(hrs) Conversion 1 3 5 Acetone to 3.7 10.5 17.6 Isopropanol (IPA), %Alpha-methylstyrene 3.8 11.4 18.7 (AMS) to Cumene, %

Example 3A

[0040] Operating condition: 5 g of Engelhard Na promoted Ni-5256, aNi/Na catalyst, and 150 g of reaction mixture at reaction temperature of81° C. and hydrogen partial pressure of 67 psig

[0041] Feed composition: 27.6 wt % of acetone, 5.1 wt % of isopropanol,17.2 wt % of cumene 3.8 wt % of Alpha-methylstyrene, 1.0 wt % ofdimethylphenylcarbinol (DMPC), 2.0 wt % of cyclohexanone+cyclohexanoland 42.4 wt % of phenol. Reaction Time (hrs) Conversion 0.5 1 2 4Acetone to <1 <1 3.1 6.6 Isopropanol (IPA), % Alpha-methylstyrene 65.895.7 98.9 98.8 (AMS) to Cumene, %

Example 3B

[0042] Operating condition: 5 g of Engelhard Na promoted Ni-5256, aNi/Na catalyst, and 150 g of reaction mixture at reaction temperature of71° C. and hydrogen partial pressure of 150 psig

[0043] Feed composition: 24.4 wt % of acetone, 9.1 wt % of isopropanol,18.2 wt % of cumene 4.1 wt % of Alpha-methylstyrene, 1.0 wt % ofdimethylphenylcarbinol (DMPC), 2.5 wt % of cyclohexanone+cyclohexanoland 39.7 wt % of phenol. Reaction Time (hrs) Conversion 0.5 1 2 4Acetone to <1 3.7 10.2 19.6 Isopropanol (IPA), % Alpha-methylstyrene85.4 98.9 99.5 99.4 (AMS) to Cumene, %

Example 3C

[0044] Operating condition: 5 g of Engelhard Na promoted Ni-5256, aNi/Na catalyst, and 150 g of reaction mixture at reaction temperature of77° C. and hydrogen partial pressure of 146 psig

[0045] Feed composition: 34.6 wt % of acetone, 0.1 wt % of isopropanol,16.5 wt % of cumene 2.5 wt % of Alpha-methylstyrene, 1.0 wt % ofdimethylphenylcarbinol (DMPC), and 44.9 wt % of phenol. Reaction Time(hrs) Conversion 1 2 3 5 Acetone to 4.5 9.3 14.8 22.8 Isopropanol (IPA),% Alpha-methylstyrene 94.6 96.4 99.1 99.6 (AMS) to Cumene, %

Example 4

[0046] A cumene hydroperoxide stream containing 80% CHP, 5% DMPC, andthe balance primarily cumene is sent to a cleavage reactor containingzeolite beta. The reaction proceeds in the liquid phase at 85° C. and 7bar (g) at a net feed weight hourly space velocity of 1.0. Arecirculated hydrogenation effluent about 30 times the mass flow of theCHP feed is combined with the CHP at the same temperature. The recyclestream contains about 48 wt.% phenol, 30 wt.% isopropanol and 12 wt.%cumene.

[0047] The liquid effluent from the cleavage reactor is fed to a fixedbed hydrogenation reactor containing Rainey nickel catalyst, in thepresence of hydrogen gas. The reaction is conducted at 120° C. and 22bar, with excess hydrogen at a hydrogen to acetone and AMS molar ratioof 8:1. Excess hydrogen is disengaged from the effluent, and recycledback to the hydrogenation reactor. Acetone conversion to isopropanol andAMS conversion to cumene are in excess of 99%. The liquid effluent ispartly recycled to the cleavage reactor as described above and partlysent to a separation stage.

[0048] The isopropanol recovered from the separation stage is fed to analkylation unit using zeolite catalyst to produce cumene. The cumeneproduced in the alkylation unit is combined with cumene recovered fromthe separation stage and the mixed stream is sent to a cumene oxidationreactor to form CHP.

[0049] It will be apparent to those skilled in the art that otherchanges and modifications may be made in the above-described apparatusand methods for hydrogenation of cleavage effluents in phenol productionwithout departing from the scope of the invention herein, and it isintended that all matter contained in the above description shall beinterpreted in an illustrative and not a limiting sense.

We claim:
 1. A method for producing phenol comprising the steps of: (a)oxidizing cumene to form cumene hydroperoxide; (b) reacting cumenehydroperoxide by acid cleavage to form an acid cleavage effluent streamwhich comprises cumene, phenol, acetone, and various byproductsincluding alpha methylstyrene; (c) separating a phenol product; and (d)hydrogenating the acid cleavage effluent stream immediately downstreamfrom said reaction step (b) in a hydrogenation reaction carried outunder hydrogenation conditions suitable for simultaneously hydrogenatingat least a part of the acetone and at least a part of the alphamethylstyrene byproducts of said acid cleavage effluent stream.
 2. Themethod according to claim 1 wherein the hydrogenation step (d) includeshydrogenating substantially all of the alpha methylstyrene.
 3. Themethod according to claims 1 or 2 wherein said hydrogenation conditionsinclude providing a molar excess of hydrogen in the hydrogenation step(d).
 4. The method according to claims 1 or 2 wherein said hydrogenationconditions include a temperature in the range of about 40° C. to 150°C., a pressure in the range of about 50 to 500 psig, and a molar ratioof hydrogen relative to the acetone and alpha methylstyrene content ofsaid acid cleavage effluent stream of at least 1 to about
 30. 5. Themethod according to claims 1 or 2 wherein the molar ratio of hydrogenrelative to the acetone and alpha methylstyrene content of said acidcleavage effluent stream is in the range of 3-10.
 6. The methodaccording to claims 1 or 2 wherein said hydrogenation step (d) iscarried out in the presence of a suitable catalyst.
 7. The methodaccording to claim 6 wherein said catalyst is selected from the groupconsisting of Group VIII elements, noble metals, nickel, copper,chromium, and claim noble metals combinations and oxides thereof.
 8. Themethod according to claim 7 wherein said catalyst is selected from thegroup consisting of Cu/Cr₂O₃, Ni/Na, Cu/Mn, and Rainey nickel.
 9. Themethod according to claim 1 further comprising the steps of: (e)separating excess hydrogen from a hydrogenation effluent stream comingfrom the hydrogenation step (d) and recycling that excess hydrogen backto the hydrogenation step (d).
 10. The method according to claims 1 or 2wherein at least a portion of the acetone in said acid cleavage effluentstream is hydrogenated to isopropanol and substantially all of the alphamethylstyrene is hydrogenated to cumene in said hydrogenation step (d).11. The method according to claims 1 or 2 wherein substantially all ofthe acetone in said acid cleavage effluent stream is hydrogenated toisopropanol in said hydrogenation step (d).
 12. The method according toclaims 1 or 2 wherein at least a portion of a liquid phase of saidhydrogenation effluent stream is recycled back to said reaction step(b).
 13. The method according to claims 1 or 2 further comprising thesteps of: (e) recovering isopropanol by distillation downstream of saidhydrogenation step (b); and (f) feeding at least a portion of therecovered isopropanol to an alkylation reactor in combination withbenzene and propylene as needed to produce the cumene for forming saidcumene hydroperoxide in the cumene oxidizing step (a).